xen msi: Handle devices with a pba of 0 (such as SRIOV)

Signed-off-by: George Dunlap <george.dunlap@xxxxxxxxxxxxx>

diff -r 33717472f37e xen/arch/x86/msi.c
--- a/xen/arch/x86/msi.c	Tue Jun 28 18:15:44 2011 +0100
+++ b/xen/arch/x86/msi.c	Thu Jun 30 13:00:08 2011 +0100
@@ -633,7 +633,6 @@ static int msix_capability_init(struct p
         u32 pba_offset;
 
         ASSERT(!dev->msix_used_entries);
-        WARN_ON(msi->table_base != read_pci_mem_bar(bus, slot, func, bir));
 
         dev->msix_nr_entries = nr_entries;
         dev->msix_table.first = PFN_DOWN(table_paddr);
@@ -646,20 +645,29 @@ static int msix_capability_init(struct p
                                      msix_pba_offset_reg(pos));
         bir = (u8)(pba_offset & PCI_MSIX_BIRMASK);
         pba_paddr = read_pci_mem_bar(bus, slot, func, bir);
-        WARN_ON(!pba_paddr);
-        pba_paddr += pba_offset & ~PCI_MSIX_BIRMASK;
 
-        dev->msix_pba.first = PFN_DOWN(pba_paddr);
-        dev->msix_pba.last = PFN_DOWN(pba_paddr +
-                                      BITS_TO_LONGS(nr_entries) - 1);
-        WARN_ON(rangeset_overlaps_range(mmio_ro_ranges, dev->msix_pba.first,
-                                        dev->msix_pba.last));
+        if ( pba_paddr )
+        {
+            WARN_ON(msi->table_base != pba_paddr);
+
+            pba_paddr += pba_offset & ~PCI_MSIX_BIRMASK;
+            
+            dev->msix_pba.first = PFN_DOWN(pba_paddr);
+            dev->msix_pba.last = PFN_DOWN(pba_paddr +
+                                          BITS_TO_LONGS(nr_entries) - 1);
+            WARN_ON(rangeset_overlaps_range(mmio_ro_ranges, dev->msix_pba.first,
+                                            dev->msix_pba.last));
+        }
+        else
+            dev->msix_pba.first = dev->msix_pba.last = 0;
 
         if ( rangeset_add_range(mmio_ro_ranges, dev->msix_table.first,
                                 dev->msix_table.last) )
             WARN();
-        if ( rangeset_add_range(mmio_ro_ranges, dev->msix_pba.first,
-                                dev->msix_pba.last) )
+
+        if ( dev->msix_pba.first
+             && rangeset_add_range(mmio_ro_ranges, dev->msix_pba.first,
+                                   dev->msix_pba.last) )
             WARN();
 
         if ( dev->domain )
@@ -669,17 +677,20 @@ static int msix_capability_init(struct p
         {
             struct domain *d = dev->domain;
 
+            /* See if any existing domains already have access to this space */
             if ( !d )
                 for_each_domain(d)
                     if ( !paging_mode_translate(d) &&
                          (iomem_access_permitted(d, dev->msix_table.first,
                                                  dev->msix_table.last) ||
-                          iomem_access_permitted(d, dev->msix_pba.first,
-                                                 dev->msix_pba.last)) )
+                          (dev->msix_pba.first &&
+                           iomem_access_permitted(d, dev->msix_pba.first,
+                                                  dev->msix_pba.last))) )
                         break;
             if ( d )
             {
                 /* XXX How to deal with existing mappings? */
+                WARN();
             }
         }
     }
@@ -839,8 +850,9 @@ static void __pci_disable_msix(struct ms
         if ( rangeset_remove_range(mmio_ro_ranges, dev->msix_table.first,
                                   dev->msix_table.last) )
             WARN();
-        if ( rangeset_remove_range(mmio_ro_ranges, dev->msix_pba.first,
-                                   dev->msix_pba.last) )
+        if ( dev->msix_pba.first
+             && rangeset_remove_range(mmio_ro_ranges, dev->msix_pba.first,
+                                      dev->msix_pba.last) )
             WARN();
     }
 }